Newman (The Missing Class) examines the proliferation of “accordion families,” in which children continue to live with their parents late into their 20s and 30s. It’s a phenomenon that spans cultures and continents, and Newman’s inquiry takes her around the world to examine how family structures are responding to societal changes. She examines how high unemployment rates, the rise of short-term employment, staggered birth rates, longer life expectancies, and the high cost of living have affected the younger generation’s transition to adulthood. While in Spain and Italy the new family dynamics mark a change from the past, they are more easily accepted than they are in Japan, where expectations for maturity and developmental milestones are more socially fixed. Newman’s interviews with parents and their cohabitating children reveal how the definition of “adulthood” is changing, from the possession of external markers (a marriage, a home) to a psychological state, an understanding of one’s place in the world and one’s responsibilities. While the book fails to provide a prescription to the accordion family, it does provide an alternative when Newman looks north to strong welfare states like Sweden and Denmark, where the government subsidizes housing and provides grants to help young adults transition more easily, a place that the U.S. can look “to see what can be done, and at what cost, to insure the orderly transition of the generations.” (Jan.)